1. Field of the Invention
The present invention relates to an absorbable bulky multifilament draw-textured yarn, and a manufacturing method and medical use thereof, and more particularly to an absorbable multifilament draw-textured yarn wherein a bulky structure is partially imparted to a draw-textured yarn (hereinafter referred to as “DTY”), such that the absorbable multifilament draw-textured yarn easily performs cell culture, cell delivery or drug delivery, and a manufacturing method and medical use thereof.
2. Description of the Prior Art
One typical tissue engineering technique comprises: collecting a required tissue from a patient body; isolating a cell from the removed tissue; proliferating the isolated cell; seeding the cell in an absorbable porous polymer scaffold; culturing the cell in vitro for a predetermined period; and transplanting the obtained hybrid-type cell/polymer structure into the human body. After the transplantation is achieved, oxygen and nutrients are provided to the transplanted cells in absorbable porous polymer due to the diffusion of body fluids until a blood vessel is newly formed. When the blood vessel is formed to which blood is supplied, the cells proliferate and differentiate to form a new tissue and organ. During the formation of new tissue and organ, the polymer scaffolds are degraded and then metabolized in the body.
Accordingly, in the field of tissue engineering, it is important to prepare an absorbable polymer scaffold that is similar to the body tissue.
In order to be used as a raw material for the polymer scaffolds, the material should have sufficient mechanical strength, such that it can properly serve as a scaffold so that tissue cells can adhere to the surface of the material and form a tissue in a three-dimensional structure. It should also serve as a middle barrier, which is positioned between a transplanted cell and a host cell. For this purpose, it should be non-toxic and biocompatible such that neither blood coagulation nor inflammatory reaction occurs after the transplantation.
In addition, such material should be absorbable so that the transplanted cell properly functions as a new tissue in the body, it is completely absorbed by the body within a desired period of time.
Typical examples of absorbable polymers which are currently generally used as raw materials for scaffolds include natural polymers, such as collagen, chitosan, gelatin, hyaluronic acid or alginic acid, and synthetic polymers, such as polylactic acid (PLA), polyglycolic acid (PGA) or poly-ε-caprolactone (PCL), or copolymers thereof.
Cell culture scaffolds prepared using such absorbable natural polymers or synthetic polymers must have high porosity and high strength so as to facilitate cell injection and proliferation.
Recently, in order to prepare a scaffold structure satisfying such requirements, researchers have made various attempts to prepare a polymer having a porous structure through various techniques. Typical examples of such techniques include: a solvent-casting and particulate-leaching technique (A. G. Mikos, etc. Polymer, 35, 1068, 1994), wherein single crystal NaCl is mixed, dried and dissolved in water; a gas foaming technique (L. D. Harris, etc., Journal of Biomedical Materials Research, 42, 396, 1998), wherein a polymer is inflated by using CO2 gas; a fiber extrusion and fabric foaming process (K. T. Paige, etc. Tissue Engineering, 1, 97, 1995), wherein a polymer fiber is formed into a nonwoven fabric to make a polymer mesh; a thermally induced phase separation technique (C. Schugens, etc., Journal of Biomedical Materials Research, 30, 449, 1996), wherein a solvent contained in a polymer solution is immersed in a nonsolvent to produce porosity; and an electrospinning technique (Korean Patent Registration No. 638736) wherein a nanofiber yarn is electrospun to form foam cells in the strand of the nanofiber yarn so as to increase the porosity of a three-dimensional cell scaffold.
In the case of the solvent-casting and particulate-leaching technique, the preparation process is easy, but there is a problem in that the pore on the surface layer is blocked, because the surface is rough and the salt remains on the surface. In the case of the gas foaming method, pores which are weakly interconnected are formed, and thus there is a limitation in terms of the injection of cells. In addition, in the case of the fiber extrusion and fabric foaming process of forming a polymer fiber into a nonwoven fabric to make a polymer mesh, a relatively high porosity can be achieved and the surface area can be optimized, but low strength is still pointed out as a problem.
Meanwhile, in the thermally induced phase separation technique, it is easy to control the size of pores, but it is difficult to apply the separation technique in practice due to the formation of pores having a relatively small size. In addition, in the electrospinning technique, it is not easy to achieve satisfactory porosity, thus making cell injection difficult.
Accordingly, with the conventional methods, it is not easy to control the pore size of the scaffold. Furthermore, the surface area and porosity of the resultant polymer scaffolds are comparatively low and the open structures are not formed well. In addition, they are disadvantageous in that there are occurrences of closed pores on the surface of the scaffolds, the process is comparatively complicated, the gas or toxic substance maybe secreted during the preparation of scaffolds, and salt remains in the scaffolds.
Accordingly, the present inventors have made efforts to solve the problems occurring in the prior art and, as a result, have prepared an multifilament yarn of less than 30 μm in diameter using a conventional absorbable polymer for medical use, and have prepared a draw-textured yarn from the multifilament yarn so as to impart bulkiness and a soft touch. Furthermore, the present inventors have found that, when bulkiness is partially imparted to the draw-textured yarn, the draw-textured yarn can easily perform cell culture, cell delivery or drug delivery during a surgical operation so as to maximize the convenience of surgery, thereby completing the present invention.